US3766294A

US3766294A - Imido alkylene substituted aromatic carbocyclic polymers

Info

Publication number: US3766294A
Application number: US00156067A
Authority: US
Inventors: J Klebe; T Windish
Original assignee: General Electric Co
Current assignee: Von Roll Isola USA Inc
Priority date: 1971-06-23
Filing date: 1971-06-23
Publication date: 1973-10-16
Anticipated expiration: 1990-10-16

Abstract

A VARIETY OF IMIDO-ALKYLENE SUBSTITUTED AROMATIC CARBOCYCLIC ORGANIC POLYMERS ARE PROVIDED, SUCH AS POLYMERS HAVING PENDANT AROMATIC CARBOCYCLIC RADICALS, SUCH AS POLYSTYRENES. THE IMIDO-SUBSTITUTED AROMATIC CARBOCYCLIC POLYMERS OF THE PRESENT INVENTION CAN BE EMPLOYED AS MOLDING COMPOUNDS, PHOTORESISTS, LAMINATES, VARNISHES, ADHESIVES, DECORATIVE COATINGS, ETC.

Description

United States Patent US. Cl. 260-78 UA 11 Claims ABSTRACT OF THE DISCLOSURE A variety of imido-alkylene substituted aromatic carbocyclic organic polymers are provided, such as polymers having pendant aromatic carbocyclic radicals, such as polystyrenes. The imido-substituted aromatic carbocyclic polymers of the present invention can be employed as molding compounds, photoresists, laminates, varnishes, adhesives, decorative coatings, etc.

This application is a continuation-in-part of our copending application Ser. No. 846,623, filed July 1, 1969, now abandoned and assigned to the same assignee as the present invention.

The present invention relates to various imidoalkylene substituted aromatic carbocyclic organic polymers.

The polyimides of the present invention can have at least one chemically combined M radical of the formula,

joined to a carbon atom on the ring of an aromatic carbocyclic radical of the organic polymer, where R is a divalent organo radical selected from hydrocarbon radicals and halogenated hydrocarbon radicals, R is a monovalent radical selected from hydrogen monovalent hydrocarbon radicals and halogenated monovalent hydrocarbon radicals.

Radicals included by R, are, for example, arylene radicals, such as phenylene, bisphenylene, naphthylene, anthrylene, etc., alkylene radicals, such as ethylene, trimethylene, tetramethylene, etc., halogenated arylene and alkylene radicals such as chlorophenylene, chloronaphthylene, chloroethylene, chlorotrimethylene, etc.; aliphatically unsaturated radicals, such as 3,766,294 Patented Oct. 16, 1973 "ice where X is a radical selected from hydrogen, lower alkyl, halogen, or mixtures thereof, such as chloro, methyl, ethyl, propyl, bromo, etc. Monovalent and hydrocarbon radicals included by R are, for example, phenyl, chlorophenyl, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, etc.

The imido-substituted "backbone polymers of the present invention having at least one chemically-combined M radical attached to an aromatic carbocyclic radical are shown by the formula,

where R" is a polyvalent aromatic organo radical selected from M-substituted aromatic carbocyclic organo radicals selected from hydrocarbon radicals and halogenated hydrocarbon radicals, and a mixture of such M-substituted aromatic carbocyclic radicals, and other polyvalent organo radicals free of M-substitution selected from hydrocarbon radicals and halogenated hydrocarbon radicals, Z is a polyvalent connective, a is a whole number having a value of 0 or 1 and n is an integer equal to 2 to 1,000 inclusive, and preferably 5 to 500 inclusive.

Radicals included by R of Formula 2 are selected from (a) M-substituted aromatic carbocyclic radicals having from 6 to 18 carbon atoms selected from hydrocarbon radicals and halogenated hydrocarbon radicals,

(b) a mixture of (a) radicals and the same aromatic carbocyclic radicals free of M-substitution, and (a), or (a) and (b) radicals,

(c) a mixture of (a), or (a) and (b) radicals, and polyvalent aliphatic radicals selected from hydrocarbon radicals and halogenated hydrocarbon radicals, where the (a) or (a) and (b) radicals are present in the mixture in an amount which is suflicient to provide for at least about 1 mole percent of (a) radicals based on the total moles of radicals in (c).

Polyvalent connectives included by Z of Formula 2 are, for example,

and mixtures thereof, where R is as previously defined.

The imido-substituted aromatic carbocyclic organic polymers of the present invention also include M-substituted polymers of the formula,

haw,

Lt" l .I.

, 3 (d) M-substituted aromatic carbocyclic radicals having from 6 to 18 carbon atoms selected from hydrocarbon radicals and halogenated'hydrocarbon radicals, and (e) a mixture of (d) radicals, and'the same aromatic carbocyclic radicals free of M-substitution,

Z is a divalent organo connective such as,

and mixtures thereof, where R" and X are as previously defined, Q is a polyvalent aliphatic, radical derived from aliphatically saturated monovalent hydrocarbon radicals and halogenated hydrocarbon radicals, and W is a monovalent radical selected from hydrogen, alkyl radicals,- halogen radicals, aliphatic ester radicals, aromatic ester radicals, amido radicals, nitrile radicals, and aliphatic nitrile radicals.

Among the carbocyclic radicals included by R" of Formula 2 there are phenylene, tolylene, xylylene, naphthylene, anthrylene, terphenylene, etc.; halogenated derivatives of such aromatic carbocyclic radicals; M-substituted derivatives of such aromatic carbocyclic radicals,

a mixture of such aromatic carbocyclic radicals, or deriva- Among the carbocyclic radicalsincluded by R' of 7 Formula 3, there are, for example, phenyl, tolyl, xylyl,

naphthyl, anthryl, etc.; halogenated derivatives of such monovalent aromatic carbocyclic radicalsvsuch as chlorophenyl bromonaphthyl, etc.; M-substituted derivatives such as,

Imido-methylene radicals included by Formula l-are, for example, a

aromatic imido-methylene compounds, for example,

I r O aliphatically unsaturated imido-methylenehalides of the formula,

As taught in our copending application Ser. No. 838,- 322, filed July 1, 1969, now abandoned and assigned'to the same assignee as the present invention, the imidomethylene substituted aromatic carbocyclic organic polymers of the present invention, for example, included by Formulas 2 and 3, can be made by eifecting contact between an aromatic carbocyclic organic polymer, and an imido-methylene compound of the formula,

in the presence of a Friedel-Crafts catalyst, where R, and R are as previously defined andY is a radical selected from hydroxy and halogen, such as chloro, bromo, fluoro, etc.

In addition to utilizing imido-methylene compounds of Formula4, there also is taught in our above-identified application Ser. No. 838,322, now abandoned, the employment of an imido-alkylene compound of the formula,

where b is an integer having a value of from 2 to 4, inclusive, and R, R and Y are as previously defined. The imido-alkylene compounds of Formula 5 can be employed with aromatic carbocyclic organic polymers included by Formula 3 in the presence of a Friedel-Crafts catalyst, such asboron tri-fiuoride to produce pendant aromatic carbocyclic polymers having at least one chemically-combined imido radical of the formula,

referred to hereinafter as an M radical, where all of the terms are shown in Formula 5. The pendant aromatic carbocyclic organic polymers are included by Formula 3, except where R' can be a mixture of aromatic carbocyclic radicals and imido-substituted aromatic carbocyclic radicals are substituted with M radicals in place of M radicals.

.Imido. radicals included by Formula 6 are, for example,

Also taught in our above-mentioned copending application is a method for introducing imido-alkylene substitution in a variety of backbone polymers, structurally similar to polymers of Formula 2 to provide for a variety of imido-substituted polyaryleneoxides, polyarylene esters, polyarylene carbonates and polyamides, as respectively shown by F. Holub and C. Emerick Ser. No. 838,316, now Pat. 3,652,710, F. Holub and M. Evans Ser. No. 838,314, now Pat. 3,652,716, Ser. No. 838,306, now Pat. 3,652,715, Ser. No. 838,315, all of which have been filed on July 1, 1969, and assigned to the same assignee as the present invention.

Among the imido-alkylene substituted aromatic carbocyclic polymers of the present invention, there are included imido-methylene substituted aromatic carbocyclic polyethers, polyesters, polycarbonates, polyamides, polyamideimides, polyimides, polysulfones, polyurethanes, polybiurets, polyxylylene, polyarylacetylenes, polysulfides, polyarylsulfides, etc. In addition, there also are included imido-alkylene substituted polystyrenes, poly(ot-methylstyrene), polymethyl(a-methylstyrene), poly(dimethylstyrene), poly(chlorostyrene), poly(dichlorostyrene), styrene copolymers with butadiene, acrylonitrile, methylmethacrylate, vinylidenechloride, maleic anhydride, vinylchloride, vinylacetate, vinylamides, a-methylstyrene, etc.

In addition to the above-described imido-methylene substituted aromatic carbocyclic polymers, there also is included in the present invention imido-methylene substitutedaromatic carbocyclic polymers in the form of random copolymers, block polymers, and graft copolymers containing at least 10 mole percent of R" radicals or R' radicals as defined in Formulas 2 and 3. For example, there are included imido-methylene substituted polystyrene-polybutadiene graft copolymers, etc.

The imido-alkylene substituted aromatic organic polymer provided by the present invention can be employed in a variety of applications depending upon such factors as the type of aromatic organic polymer, the degree of imido-alkylene substitution in the polymer, and whether the imido-alkylene radicals, as shown by Formulas 1 and 6, are aliphatically unsaturated, or free of aliphatic unsaturation. For example, in instances where the aromatic organic polymer has chemically combined imido-alkylene radicals of Formula 1 or 6 which are aliphatically unsaturated, these materials can be employed in a variety of applications such as molding compounds, varnishes, adhesives, laminating compounds, solvent-resistant coatings, dielectrics, insulating coatings, and several other applications normally requiring free radical and high energy electron curable materials convertible from the thermoplastic to the thermoset state, as more particularly shown for particular aromatic organic polymers described in the aforementioned copending applications. In instances where the aromatic organic polymers are substituted with imido-alkylene radicals of Formulas 1 and 6 which are free of aliphatic unsaturation, such aromatic organic polymers can provide for solvent-resistant coating compounds, molding resins, high temperature and oxidatively stable fibers and films, etc.

The imido-alkylene substituted aromatic organic polymers of the present invention can be blended with various aliphatically unsaturated organic materials, such as aliphatically unsaturated organic monomers and certain aliphatically unsaturated organic polymers as well as organic polymers free of aliphatic unsaturation. Blends of the imidoalkylene substituted aromatic organic polymers and the aforementioned organic monomers or polymers can be made over a wide proportion by weight. Experience has shown that there should be employed at least about 5 percent, by weight, of the imido-alkylene substituted aromatic organic polymer to provide for cured products having improved characteristics. For example, if the imido-alkylene aromatic polymer has chemically combined aliphatically unsaturated imidoalkylene radicals of Formula 1, the blend of the imido-alkylene substituted aromatic polymer with the aforementioned organic materials can be employed in making laminating compounds, solventless varnishes, molding compounds, coating compositions, etc., depending upon the proportions of the imido-aliphatically unsaturated imido-alkylene substituted aromatic organic polymer and the organic polymer or monomer utilized in the blend. Those skilled in the art would know, for example, that as the proportion of the imidoalkylene aromatic organic polymer having aliphatically unsaturated imido-alkylene radicals increased with respect to either the organic monomer or polymer in the blend, particularly where the mole percent substitution of the aliphatically unsaturated imido-alkylene radi cal on the aromatic organic polymer exceeded 25 mole percent or more, the degree of crosslinking of the blend would be sufficiently high to make the resulting cured product an ideal solvent-resistant coating or insulating material.

Included by the aliphatically unsaturated monomers that can be employed in combination with the imidoalkylene substituted aromatic organic polymers of the present invention are, for example, styrene, bismaleimide, N-phenylmaleimide, vinylchloride,isobutylene, butadiene, isoprene, chlorotrifluoroethylene, 2 methylpentene 1; vinyl esters of organic carboxylic acids such as vinylformate, vinylacetate, acrylonitrile, vinylmethyl, methyl, butyl, etc., esters of acrylic and methacrylic acids, etc.; divinylbenzene, triallylcyanurate, triallyltrimellitate, and N-vinylphthalimide, N-allylphthalimide, N-allyltetrachlorophthalimide, vinylsiloxanes, etc. Among the organic polymers that can be employed in combination with the imido-alkylene substituted aromatic organic polymers of the present invention are, for example, polyvinylchloride,

polyethylene, polypropylene, polysulfones, polystyrene,

polyurethane, organopolysiloxanes, polyesters, polyphene ylene oxides, epoxide resins, etc.

Cure of the imido-alkylene substituted aromatic organic polymer, or blend thereof with any of the aforementioned organic monomers or polymers, or combination thereof, can be effected with conventional free radical initiators at temperatures of from 50 C. to 300. C., while 100 C. to 200 C. has sometimes been found to be more desirable. Acceleration of the cure of the imido-alkylene substituted aromatic organic polymer, or blend thereof, can be achieved with organic peroxides, such as .dicumyl peroxide, benzoyl peroxide, tertiary butylperbenzoate, tertiary alkylperoxycarbonate, etc.'The peroxides canbe employed from about 0.1 percent to about percent by weight, based on the total weight of the blend. In addition, high temperature radical sources can also be employed, such as the commercially available azodicarbon amides, 2,5-dimethyl, -2,5-bis(tert-butylperoxyhexane), etc. In addition, the imido-al'kylene substituted aromatic polymers or blends thereof, in addition to being curable by the aforementioned free radical initiators, can ,be cured with heat or radiation with high energy electrons,

X-rays, ultraviolet lighting, etc., depending upon the cross In addition to the aforementioned aliphatically unsat-,

urated monomers and organicpolymers which can be blended with the imido-alkylene substituted aromatic, or-

ganic polymers of the presentinvention, there can be employed, by weight, fillers in proportions of from 0 to 200 parts of filler, per 100 parts of the imido-alkylene substituted aromatic organic polymer. Included among.

the fillers which can be employed are, for example, clay,

ground quartz, silica, sand, carbon black, glass fibers, glass beads, carbon fiber, asbestos, etc. In addition, other ingredients such as solvents at from 60 percent to 90 percent by weight of the resulting curable composition also can be employed such as N-methyl pyrrolidone, dimethylacetamide, toluene, methylenechloride, as well as plasticizers such as trioctylphthalate, etc.

In order that those skilled in the art will be better able to practice the invention, the following examples,

are given by way of illustration and not by way of limitation. Stirring of the reactants occurred during the addition of the Friedel-Crafts catalyst. All parts are by weight.

EXAMPLE 1 Boron trifluoride was passed into a solution at 55 C;

spectrum of the product which showed a strong carbonyl absorption at 1,720 cm.- the product was identified as a maleimidomethylene substituted polystyrene having about 25 mole percent of thephenyl radicals substituted with maleimidomethylene radicals based on the total moles of imido-substituted and unsubstituted phenyl radicals in the polystyrene. The identity of the polymer and the degree of substitution was further confirmed by ele- 7 mental analysis. A thin film of the product containing about 1 percent of benzophenone was subjected to ultraviolet irradiation for 20 seconds. Those parts of the film that were exposed to the ultraviolet light were found to be insoluble in organic solvents. The product is usefulas a photoresist.

8 EXAMPLE 2 Boron trifluoride was slowly bubbled into a solution of 5 parts of polystyrene having a molecular weight of about 100,000 and 2.65 parts of N-chloromethyl-5-norbornene- 2,3-dicarboxylic imide and 70 parts of tetrachloroethane and 30 parts of nitrobenzene while the temperature ismaintained at 55 C. over a period of about 12 hours. The imido-methylene alkylating agent was made from N-hydroxymethyl-5-norbornene-2,3-dicarboxylic 'imide employing thionylchloride in accordance with the method of the prior art. The mixture was then poured into methanol to effect the precipitation of the product. Based on method of preparation, the product was, a polystyrene having chemically combined 3,6 methano 1,2,3,6 tetrahydrophthalimidomethylene radicals. The identity of the product was confirmed by its infrared spectrum.

EXAMPLE 3 Boron trifluoride was slowly introduced into a mixture phthalimido-methylen'e radicals. The identity of the prod-' not was confirmed by the characteristic carbonyl absorb ance at 1,715 cm. in its infrared spectrum. The polymer is useful as a molding composition with increased soften ing temperature as compared with unsubstituted polystyrene.

EXAMPLE 4 Boron trifluoride is slowly introduced into; a 10 percent solution of styrene-butadiene copolymer and N-chloromethylmaleimide in chlorobenzene. The styrene-butadiene copolymer is prepared in accordance with the method of Amos et al., US. Pat. 2,694,692 utilizing a mixture of 90 mole percent of butadiene and 10 mole percentof styrene. The N-chloromethylmaleimide is present in the mixture at about an equal molar amount of the styrene utilizedin making the copolymer. Thev solution is stirred. whilethe boron trifluoride is introduced over a period of about 15 hours at 25 C. The mixture is then poured into methanol and a product is precipitated. Based on method of preparation, the product is a styrene-butadi'en'e copolymer having chemically combined styrylradicals substituted with maleimidomethylene radicals.

A solution of the maleimidomethylene substituted polymer in chlorobenzene is poured onto an aluminum sub- 7 strate and the solvent is allowed to evaporate at a temperature below its boiling point. The resulting film containing about 2 percent by weight of, benzophenone is irradiated with ultraviolet light for a period of about 2 minutes. The film is found to be insoluble in chlorobenzene andexhibits valuable dielectric and insulating prop erties.

EXAMPLE 5 N-(Z-chloroethyl)tetrahydrophthalimide was madeby the following procedure:

A mixture of 10 parts of N-'( 2-hydroxyethyl )tetrahydrophthalimide, which had been prepared from tetrahydrophthalic anhydride and ethanolamine'by standard procedure, was refluxed with 25 parts of thionyl chloride for about Zhours. Excess thionyl chloride was distilled and the residue purified by recrystallization from methanol.

There was obtained a crystalline product having a melting point of about C. Based on method of preparation and the aforementioned melting point, the product was N-(2-chloroethyl)tetrahydrophthalimide.

A mixture was made of,2.5 parts of a polystyrene hava ing a molecular weight of about 100,000, 2 partsof N-(2- chloroethyl)tetrahydrophthalimide and 35 parts of anhywhere MQ is a tetrahydrophthalimidoethyl radical, which are chemically combined with about 75 mole percent of styrene units of the formula,

A film of the imido-substituted polystyrene is cast from a tetrachloroethane solution onto an aluminum substrate.

The film is exposed to fi-radiation to a dosage of 50 mr. It is found to be insoluble in several organic solvents including tetrachlorethane and useful as an organic solvent resistant coating.

EXAMPLE 6 There was added to a solution of 2 parts of polystyrene in about 50 parts'of chloroform, 2 parts of N-hydroxymethylhexachloro--norbornene-2,3-dicarboxylic imide in the presence of boron trifluoride, which was employed at up to saturation in the mixture. The mixture was agitated at room temperature for about 4 hours. A product was recovered by addition to methanol, which was in the form of a colorless polymer showing strong carbonyl absorption at 1720 cm.- Based on method of preparation, the product was a polystyrene having phenyl radicals substituted with hexachloro 5 norbornene 2,3 dicarbonyl imidomethyl radicals. The polymer was cast onto a film from chloroform, which was converted to the insoluble state when exposed to ultraviolet light for about 20 seconds as described previously in the presence of a 1% by weight benzophenone photoinitiator.

EXAMPLE 7 There was added to a solution of 1 part of a polychloro styrene, EXP-MX4616 from Dow Chemical Company, in about 10 parts of chloroform, 0.24 part of N-hydroxymethylmaleimide. Boron trifluoride was passed into the resulting mixture at room temperature with stirring. Upon effecting a detectable increase in viscosity of the solution, methanol was added in an amount to effect the precipitation of product. Based on method of preparation, the product was a maleimidomethyl substituted polychlorostyrene. Elemental analysis of the product showed that it contained about 6 mole percent of maleimidomethyl substituted phenyl radicals.

A film of the product was cast from a chloroform solution containing a 1% concentration of benzophenone. There was obtained a film exhibiting a substantial increase in solvent resistance when it was exposed to ultraviolet light for a period of about 20 seconds. This established that the imido-substituted polystyrene could be employed as a photoresist.

1 0 EXAMPLE 8 There is added 2 parts of boron trifluoride to a solution at room temperature of 10.4 parts of polystyrene and 1.3 parts of N-hydroxymethyl maleimide, dissolved in about 20 parts of methylene chloride and 30 parts of nitromethane. A product is obtained by pouring the resulting mixture into methanol after it is stirred for about fifteen hours. The product is dried in vacuo at 50 C. Based on method of preparation, the product is a maleimidomethyl substituted polystyrene.

The above maleimidomethyl substituted polystyrene is blended with equal parts by weight of poly(2,6-dimethylphenyleneoxide) having a molecular weight of about 50,- 000. A finished structure is obtained when the blend is mloded at a temperature of about ISO-200 C. for about 60 minutes. The part exhibits valuable solvent resistance and can be employed in making automobile components requiring high performance.

EXAMPLE 9 A solution of the above described maleimidomethyl substituted polystyrene is prepared by blending 1 part of the polystyrene with 9 parts of styrene monomer. There is added to the solution, 1% by weight of benzoyl peroxide. The resulting composition is poured into a mold and heated at C. for about 6 hours. There is obtained a finished reproduction of the mold. The part exhibits valuable solvent resistant properties.

Although the above examples are limited to only a few of the imido alkylene substituted aromatic carbocyclic polymers which can be made in accordance with the practice of the invention, it should be understood that the present invention is directed to a much broader class of imidosubstituted aromatic carbocyclic polymers, which can be made by effecting reaction between polymers included by Formula 2 and imido alkylating agents as shown by Formula 5.

We claim: v

1. A film forming aromatic carbocyclic organic polymer which can be employed as a molding resin, or solvent resistant coating compound, which consists essentially of from 5 to 500 chemically combined units selected from the group consisting of,

and a mixture of (a) and (b), where at least one mole percent of such units have an imido-alkylene group of the formula,

directly joined to a ring carbon atom of an aromatic carbocyclic radical, where R is a divalent organo radical free of aliphatic unsaturation selected from the group consisting of hydrocarbon radicals and halogenated hydrocarbon radicals, R is selected from the group consisting of hydrogen, monovalent hydrocarbon radicals and halogenated monovalent hydrocarbon radicals, R' is a monovalent organo radical selected from the group consisting of hydrocarbon radicals or halogenated radicals, b is an integer having'a value of from l to 4;inclusive," and Z; 1 "unsaturated-hydrocarhon radical, R'cis selected from the, is adivalent organo radical having'the formula I group;consistingrofhydrogen; 'monovalentihydrocarbon X X X 1 1 i radicals and halogenated monovalent' hydrocarbon radi-Z cals, R",f is a rnonovalent organo radical selected from the 7 I 5 group consistin of hydrocarbon radicals or halogenated V g V H I H l 7 hydrocarbonradicals, b is an integer having avalueof and X is a radical selected from the group consisting of {from 1 4, inclusive, is divalfint'organo radical hydrogen, alkyl, and mixtures thereof. j ihaving t formula 2. A composition in accordance with claim 1, where the 7 V a 1 film forming'aromatic carbocyclic organic polymer is an 10 1 l X imido alkyl substituted halogenated polystyrene. 7 1 I 1 J 1 l 3. A composition in accordance with claim 1, where I the aromatic carbocyclic organic polymer is substituted 7 H V 1 with a halogenated imido alkyl "group; I

4. An imido-methylene substituted styrene butadiene and X is a radical selected from thet'group consisting of copolyrner in accordance with clair' nlll 1 hydrogen, alkyl, and mixiures thereof: 1

5. A film forming polystyrenein accordance with; 7. A rnaleimido-methylene' substituted polystyrene in claim 1; '1 '7 accordance withclairn 6. V 6. A film forming aromatic carbocyclic organic' poly'j 8. A maleimidomethylene substituted polystyrene in mer which can be employed asarnolding resin, or solvent 20 accordance with clairn6. a l' resistantccoatin'g compound,:which consists essentiall'y'off 1 9. A film formin organiopolymer in accordance with from 5' to 500' chemically combined units selected from claim 6, havingmonovalent aromaticcarboeycIic'organic" the group consisting of, 1 radicals substituted with imido-methylene radicals.

X g a 10. Afilrnformingimidoemethylene sljibstituted organic 1 a V 125 polymers in accordance with claim '6, which is substituted J V 'with aliphatically unsaturated imido-methylene radicals H o y LRC; R; ,7 r 1,1. A-phthalimidoethylene substituted polystyrene: in

" X"[ r V w Qaccordancewith claim 6.

' (b)' h r and a mixtureof (a) and :(b); whereat least one mole l 1 Rel everices Cited V UNITED STATES ATEN'rs,

r ly 'i i a i g carbon: atom f n a o a i Y 85.7, 86.7, 93.5 A, 88.1 PN, 880, 881,884,885, 897, 899::

carbocyclic radical, where Rtis a divalent "aliphatically